The study was designed to analyze childhood disorders by assessing stability and change in the behavior problems of 6- to 11-year-old and 12- to 16-year-old children seen in a community child guidance clinic. Parents of 468 children completed the Child Behavior Checklist at intake and again 6 months and 18 months thereafter. Our findings show that the question of stability and change in clinically relevant behaviors cannot be answered in an all-or-none fashion. Many behavior problems appeared to follow a developmental trend, while others showed great stability despite efforts to change them. The group average of many items remained at a constant level, but individual children did not necessarily retain stable ranks within their group. Other behaviors showed the opposite pattern, with significant decreases in mean scores, but stable rank ordering of individuals within their group.